1. Field of the Invention
The present invention relates to a driver including a voltage-follower-type operational amplifier used in driving data lines (signal lines) of a display apparatus such as a liquid crystal display (LCD) apparatus.
2. Description of the Related Art
In a display apparatus such as an active matrix type LCD apparatus where a plurality of pixels each formed by one thin film transistor (TFT) and one pixel capacitor are provided at intersections between a plurality of data lines (or signal lines) and a plurality of gate lines (or scan lines), drivers are provided to drive the data lines.
A prior art driver is constructed by a voltage-follower-type operational amplifier which is divided into an input stage formed by two parallel differential amplifiers for realizing an input wide range and an output stage formed by a single-end push-pull circuit for realizing an output wide range. Also, in order to rapidly converge a transient state to an equilibrium state, the driving ability is enhanced by increasing bias currents flowing through the differential amplifiers of the input stage using the feedback control of the output stage (see: JP-A-11-088076). This will be explained later in detail.
In the above-described prior art driver, however, when a transient state is rapidly converged to an equilibrium state, the driving ability is enhanced by increasing the bias currents, which would increase the power consumption.